George d



GEORGE D. VAN ARSDALE, OF NEW YORK, N. Y.

No drawing.

To all whom it may concern Be it known that I, GEORGE D. VAN Ans- DALE, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Methods of Preventing Disintegration of Anodes, of which the following is a specification.

This invention relates to an improved method of use of graphite anodes in the electrolysis of solutions, more particularly copper solutions, as applied in the leaching of copper ores, in such a way that-the rapid disintegration, which has heretofore prevented the use of graphite or other insoluble anodes, may be entirely prevented.

Heretofore, to the best of my knowledge, no satisfactory anode, for use in the electrolysis of solutions of copper, particularly of sulphate solutions, has been known. Lead, on the whole, has given the best results for sulfate solutions, while in almost all cases carbon is the only substance that can be employed in chlorid solutions. For sulfate solutions, however, even the best qualities of carbon are eventually destroyed. Graphitized carbons have given satisfactory results with chlorid, but not with sulfate solutions. Practically lead anodes have been used, but these are more or less readily disintegrated and require a high current voltage. Fused magnetite anodes are also in use, but with these the voltage is high.

I have discovered that the disintegration, for example, of graphite or carbon anodes in chlorid, and especially sulfate solutions, is probably almost entirely due to the mechanical disintegrating effect of the bubbles of gas evolved in the pores ofrthe anodes, at their surface, during electrolysis, and that by preventing such evolution of gas, disintegration of the anodes may be entirely prevented. The means which I employ for preventing the evolution of as, 'at the anode, is the presence, during e eetrolysis, of a suflicient amount of a depolarizing agent or agents in the solutions treated. When the depolarizers are present, in sufficient amount, the

Specification of Letters Patent.

- depolarizers Patented Aug. 8, 1916.

- Application filed August 2, 1915. Serial No. 43,300.

oxygen or other gases formed at the anode, which would otherwise be evolved in the free state as bubbles, unite in the nascent state with the depolarizing agents and their evolution in the free state is thereby entirely prevented. As a result, there is no disintegration or other appreciable deterioration of the anodes.

Various depolarizers or combinations of may be employed, those preferred being salts of iron in the ferrous condition, or sulfur dioxid, or both together. These may be employed with various anodes, although I prefer to use graphite as my anode material since, when working in this way, the voltage is considerably lower than with other materials. However, by employing depolarizers in sufiicient amount with lead anodes, the peroxidation and deterioration of the lead may be prevented.

While the deterioration of anodes hitherto has been most marked with sulfate solutions, there is also deterioration, although to a less degree, with chlorid solutions, and since deterioration may be prevented in both classes of solutions, by my method, I do not wish to confine the application'of this invention to any single class of solutions, anodes or depolarizers. It is also probable that where the use of insoluble anodes is needed for solutions of metals other than copper, this reaction will also be valuable in preventing -disintegration.

I have found, by experiment, that I can prevent-disintegration and deterioration of anodes of either graphite, or lead in both sulfate and chlorid solutions of copper, as well as in solutions in other metals by the use of depolarizers in suflicient amount. I have further found that in all of the above instances, sulfur dioXid or ferrous sulfate forms an eflicient depolarizer or that both may be used together with equally good results.

Having thus described the invention, what is claimed as new is:

1. The method of preventing disintegration of anodes in the electrolysis of copper solutions, which consists in electrolyzing at I - such solutions in the presence at the anode lyzing such solutions in the presence at'the of ferrous sulfate and sulfur dioxid in suflianode of ferrous sulfate and sulfur dioxid oient amounts to prevent the evolution of in sufiicient amounts to prevent the evolu- 10 free oxygen at the anode. tion of free oxygen at the anode.

2. The method of preventin disintegra- In testimony whereof I afiix my signature. tion-of graphite anodes in the e ectrolysis of I copper solutions, which consists in electro GEORGE D. VAN ARSDALE. [L. 8-]

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